pyfuncol
A Python functional collections library. It extends collections built-in types with useful methods to write functional Python code. It uses Forbidden Fruit under the hood.
pyfuncol provides:
- Standard "eager" methods, such as
map,flat_map,group_by, etc. - Parallel methods, such as
par_map,par_flat_map, etc. - Pure methods that leverage memoization to improve performance, such as
pure_map,pure_flat_map, etc. - Lazy methods that return iterators and never materialize results, such as
lazy_map,lazy_flat_map, etc.
pyfuncol can also be used without forbiddenfruit.
Installation
pip install pyfuncol
Usage
Note: If you are not using forbiddenfruit, the functions will not extend the builtins. Please see here for usage without forbiddenfruit.
To use the methods, you just need to import pyfuncol. Some examples:
import pyfuncol
[1, 2, 3, 4].map(lambda x: x * 2).filter(lambda x: x > 4)
# [6, 8]
[1, 2, 3, 4].fold_left(0, lambda acc, n: acc + n)
# 10
{1, 2, 3, 4}.map(lambda x: x * 2).filter_not(lambda x: x <= 4)
# {6, 8}
["abc", "def", "e"].group_by(lambda s: len(s))
# {3: ["abc", "def"], 1: ["e"]}
{"a": 1, "b": 2, "c": 3}.flat_map(lambda kv: {kv[0]: kv[1] ** 2})
# {"a": 1, "b": 4, "c": 9}pyfuncol provides parallel operations (for now par_map, par_flat_map, par_filter and par_filter_not):
[1, 2, 3, 4].par_map(lambda x: x * 2).par_filter(lambda x: x > 4)
# [6, 8]
{1, 2, 3, 4}.par_map(lambda x: x * 2).par_filter_not(lambda x: x <= 4)
# {6, 8}
{"a": 1, "b": 2, "c": 3}.par_flat_map(lambda kv: {kv[0]: kv[1] ** 2})
# {"a": 1, "b": 4, "c": 9}pyfuncol provides operations leveraging memoization to improve performance (for now pure_map, pure_flat_map, pure_filter and pure_filter_not). These versions work only for pure functions (i.e., all calls to the same args return the same value) on hashable inputs:
[1, 2, 3, 4].pure_map(lambda x: x * 2).pure_filter(lambda x: x > 4)
# [6, 8]
{1, 2, 3, 4}.pure_map(lambda x: x * 2).pure_filter_not(lambda x: x <= 4)
# {6, 8}
{"a": 1, "b": 2, "c": 3}.pure_flat_map(lambda kv: {kv[0]: kv[1] ** 2})
# {"a": 1, "b": 4, "c": 9}pyfuncol provides lazy operations that never materialize results:
list([1, 2, 3, 4].lazy_map(lambda x: x * 2).lazy_filter(lambda x: x > 4))
# [6, 8]
list({1, 2, 3, 4}.lazy_map(lambda x: x * 2).lazy_filter_not(lambda x: x <= 4))
# [6, 8]
list({"a": 1, "b": 2, "c": 3}.lazy_flat_map(lambda kv: {kv[0]: kv[1] ** 2}))
# [("a", 1), ("b", 4), ("c", 9)]
set([1, 2, 3, 4].lazy_map(lambda x: x * 2).lazy_filter(lambda x: x > 4))
# {6, 8}Usage without forbiddenfruit
If you are using a Python interpreter other than CPython, forbiddenfruit will not work.
Fortunately, if forbiddenfruit does not work on your installation or if you do not want to use it, pyfuncol also supports direct function calls without extending builtins.
from pyfuncol import list as pfclist
pfclist.map([1, 2, 3], lambda x: x * 2)
# [2, 4, 6]API
For lists, please refer to the docs.
For dictionaries, please refer to the docs.
For sets and frozensets, please refer to the docs.
For more details, please have a look at the API reference.
We support all subclasses with default constructors (OrderedDict, for example).
Documentation
See https://pyfuncol.readthedocs.io/.
Compatibility
For functions to extend built-ins, Forbidden Fruit is necessary (CPython only).
Contributing
See the contributing guide for detailed instructions on how to get started with the project.
License
pyfuncol is licensed under the MIT license.